Minimally invasive apparatus for implanting a sacral stimulation lead

ABSTRACT

Methods and apparatus for implanting a stimulation lead in a patient&#39;s sacrum to deliver neurostimulation therapy that can reduce patient surgical complications, reduce patient recovery time, and reduce healthcare costs. A surgical instrumentation kit for minimally invasive implantation of a sacral stimulation lead through a foramen of the sacrum in a patient to electrically stimulate a sacral nerve comprises a needle and a dilator and optionally includes a guide wire. The needle is adapted to be inserted posterior to the sacrum through an entry point and guided into a foramen along an insertion path to a desired location. In one variation, a guide wire is inserted through a needle lumen, and the needle is withdrawn. The insertion path is dilated with a dilator inserted over the needle or over the guide wire to a diameter sufficient for inserting a stimulation lead, and the needle or guide wire is removed from the insertion path. The dilator optionally includes a dilator body and a dilator sheath fitted over the dilator body. The stimulation lead is inserted to the desired location through the dilator body lumen or the dilator sheath lumen after removal of the dilator body, and the dilator sheath or body is removed from the insertion path. If the clinician desires to separately anchor the stimulation lead, an incision is created through the entry point from an epidermis to a fascia layer, and the stimulation lead is anchored to the fascia layer. The stimulation lead can be connected to the neurostimulator to delivery therapies to treat pelvic floor disorders such as urinary control disorders, fecal control disorders, sexual dysfunction, and pelvic pain.

This is a continuation-in-part of U.S. patent application Ser. No.09/713,598 filed Nov. 15, 2000 for MINIMALLY INVASIVE METHOD FORIMPLANTING A SACRAL STIMULATION LEAD.

CROSS REFERENCE

This disclosure is related to the following co-pending applicationentitled “Minimally Invasive Surgical Techniques For Implanting DevicesThat Deliver Stimulation To The Nervous System” by inventors Gerber etal. (application Ser. No. 09/489,544; filed Jan. 31, 2000), which is notadmitted as prior art with respect to the present disclosure by itsmention in this cross-reference section.

BACKGROUND OF THE INVENTION

This disclosure relates to apparatus in the form of a kit of medicalinstruments used for surgically implanting an electric neurostimulationlead in the human sacrum.

The medical device industry produces a wide variety of electronic andmechanical devices for treating patient medical conditions. Dependingupon the medical condition, medical devices can be surgically implantedor connected externally to a patient receiving treatment. Clinicians usemedical devices alone or in combination with drug therapies and surgeryto treat patient medical conditions. For some medical conditions,medical devices provide the best, and sometimes the only, therapy torestore an individual to a more healthful condition and a fuller life.Conditions that medical devices can effectively treat include pelvicfloor disorders.

Pelvic floor disorders adversely affect the health and quality of lifeof millions of people. Pelvic floor disorders include urinary controldisorders such as urge incontinency, urge frequency, voiding efficiency,fecal control disorders, sexual dysfunction, and pelvic pain.Individuals with urinary control disorders often face debilitatingchallenges in their everyday lives. These individuals can be preoccupiedwith trips to the bathroom, fears of embarrassment, and sleeplessnights. Some suffers become so anxious that they become isolated anddepressed. Pelvic floor disorders can be treated with a variety oftherapeutic options such as behavior modification including biofeedback,pharmacological treatment, mechanical intervention such asself-catheterization, physical appliances such as diapers, and surgicalintervention. Surgical treatments are the most invasive and are oftenconsidered after other therapies have proven ineffective.

One surgical technique to treat urinary control disorders is theimplantable InterStim® therapy, available from Medtronic, Inc., whichapplies mild electrical stimulation to the sacral nerves in the lowerregion of the spine to influence behavior of structures such as thebladder, sphincter and pelvic floor muscles. Generally, implantation ofInterStim therapy involves surgically implanting a stimulation lead nearthe sacral nerves. The stimulation lead is a very small, insulatedelectrical conductor with electrical stimulation contacts on the distalend placed near the sacral nerves and an electrical connector on theopposite proximal end of the lead. The lead electrical connector istypically connected to a small extension, and the extension is connectedto a small neurostimulator that operates similar to a cardiac pacemakerby delivering occasional small electrical pulses that sometimes create atingling sensation felt by the patient. The stimulation lead, leadextension, and neurostimulator are all implanted in the patient in amanner that is typically not perceptible by others. InterStim therapycan improve the condition of a pelvic floor disorder patient and allowthe patient to lead a full life. Also, InterStim therapy isnondestructive and reversible.

Previous surgical methods and apparatus used to implant aneurostimulation lead in a patient's sacrum to treat pelvic floordisorders have been invasive by requiring a large sacral incision in aprocedure known as dissection. FIG. 1 a (prior art) shows a sacraldissection. Dissection involves making a midline incision over thesacrum from a little below S4 up to S1 that in an adult ranges fromabout 7.62 cm (3.0 inches) to 12.7 cm (5.0 inches). After the incisionis made, the fascia lateral to the midline is cleaned off and divided inthe direction of the incision approximately one finger width lateral tothe midline. Next, the paraspinal muscle fibers are split and sharplyretracted. Once the muscle fibers are retracted, the sacral foramen isexposed while preserving the periosteum. Next, the desired foramen islocated by observing anatomical landmarks and palpating for amarble-board-like depression in the posterior sacral surface. FIG. 1 b(prior art) shows a foramen dissection. Once the desired foramen islocated, another small incision is made over the desired foramen that islarge enough to allow insertion of the stimulation lead. The stimulationlead is inserted through the incision. Surgically implanting thestimulation lead in this manner near the patient's sacral nerve cancause patient complications, create significant patient's recovery time,and create a significant expense to the healthcare system. An example ofthe previous surgical method to implant a neurostimulation lead isdescribed in Medtronic, “InterStim® Therapy Sacral Nerve Stimulation ForUrinary Control Therapy Reference Guide,” Section 5 InterStim DeviceImplantation Procedure, pp. 51-52 (1999).

For the foregoing reasons, there is a need for a less invasive surgicalinstrument set for performing a method of implanting a neurostimulationlead in a patient through a foramen of the sacrum in relation to asacral nerve, whereby patient surgical complications, surgical recoverytime, and surgical costs are reduced while maintaining the substantialpatient benefits of neurostimulation of the sacral nerve.

SUMMARY OF THE INVENTION

The minimally invasive instrument set for implanting sacral stimulationleads comprises at least a needle and a dilator that are particularlyadapted to enable introduction of a neurostimulation lead into a foramento locate a distal neurostimulation lead electrode(s) in operativerelation to a sacral nerve. The needle is adapted to be grasped by amedical clinician with the needle distal end directed toward andinserted through an entry point of the skin or a skin incision posteriorto the sacrum and guided along an insertion path into a foramen tolocate at least a distal portion of the needle extending alongside asacral nerve and a proximal portion of the needle extending from theentry point away from the patient's skin. The dilator is adapted to beinserted over the needle proximal end to locate the needle within thedilator body lumen and to be advanced distally over the needle throughthe insertion path to dilate the insertion path to the dilator diameter.The needle is adapted to be withdrawn through the dilator body lumen sothat the stimulation lead can be advanced through the dilator body lumento locate the stimulation lead electrode into operative relation to thesacral nerve. The dilator is adapted to be withdrawn over thestimulation lead body.

Alternatively, the minimally invasive instrument set comprises a needlehaving a needle lumen, a dilator and a guide wire that are particularlyadapted to enable introduction of a neurostimulation lead into aforamen. The guide wire has a guide wire diameter sized to fit throughthe needle lumen and a guide wire length extending between a guide wireproximal end and a guide wire distal end. The guide wire is adapted tobe inserted through the needle lumen to locate a distal portion of theguide wire through the foramen of the sacrum after the needle is guidedinto position. The needle is adapted to be withdrawn over the guidewire, and the dilator is adapted to be inserted over the guide wireproximal end to locate the guide wire within the dilator body lumen andto be advanced distally over the guide wire through the insertion pathto dilate the insertion path to the dilator diameter. The guide wire isadapted to be withdrawn through the dilator body lumen, the stimulationlead is adapted to be advanced through the dilator body lumen to locatethe stimulation lead electrode into operative relation to the sacralnerve, and the dilator is adapted to be withdrawn over the stimulationlead body.

In a further preferred embodiment, the dilator comprises the assembly ofa dilator body and a dilator sheath that are inserted through the skinas an assembly and are separated to enable introduction of theneurostimulation lead through the dilator sheath lumen. The dilator isadapted to be introduced over the needle or guide wire as abovedescribed, whereupon the dilator body and guide wire are withdrawn,leaving the dilator sheath. The stimulation lead is adapted to beadvanced through the dilator body lumen to locate the stimulation leadelectrode into operative relation to the sacral nerve, and the dilatorsheath is adapted to be withdrawn over the stimulation lead body.

The needle, dilator and guide wire are all preferably formed of aconductive material insulated along the exposed lengths thereof butexposed at or along the proximal and distal ends thereof so as to becapable of being used to conduct test stimulation to the sacral nerve toassess the efficacy of stimulation prior to implantation of theneurostimulation lead and to establish the depth of positioning of theneurostimulation lead electrode.

The needle, dilator, guide wire and neurostimulation lead bodies aremarked with depth indicators that are correlated to one another so thatthe depth of insertion from the skin of each is ascertainable from theexposed marking so as to assure that the clinician extends eachinstrument to the same depth to properly locate the neurostimulationlead electrode in operative relation to the sacral nerve.

The guide wire may be relatively stiff to prevent bending or flexible toenable a degree of bending.

Additionally if the clinician desires to separately anchor thestimulation lead, an incision can be created through the entry pointfrom an epidermis to a fascia layer. The stimulation lead is anchored tothe fascia layer. Finally, the incision is closed. The minimallyinvasive instrumentation set and method of sacral stimulation leadimplantation can be practiced in a wide variety of embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows a prior art sacral dissection;

FIG. 1 b shows a prior art foramen dissection;

FIG. 1 c shows an environment of a patient undergoing a sacralstimulation procedure;

FIG. 2 shows an embodiment of an implanted neurostimulator;

FIGS. 3 a-3 g show some surgical tools that can be used to perform theminimally invasive method;

FIG. 4 shows a flowchart of a first minimally invasive methodembodiment;

FIG. 5 a shows a flowchart of a second minimally invasive methodembodiment;

FIG. 5 b shows a needle being inserted into a foramen embodiment;

FIG. 5 c shows a cross section view of FIG. 5 b;

FIG. 5 d shows the needle being used as a guide for a larger needleembodiment;

FIG. 5 e shows removal of a stylet and insertion of a stimulation leadembodiment;

FIG. 5 f shows another view of insertion of the stimulation leadembodiment;

FIG. 5 g shows removal of the needle and insertion of an anchorembodiment;

FIG. 5 h shows fixation of the anchor embodiment;

FIG. 5 i shows another stimulation lead fixation embodiment;

FIG. 5 j shows another view of the stimulation lead fixation embodimentshown in the FIG. 5 i embodiment;

FIG. 5 k shows an anchored stimulation lead that is tunneled forconnection to a medical device;

FIG. 6 a shows a flowchart of a third minimally invasive methodembodiment;

FIG. 6 b shows a patient having a needle inserted posterior to thepatient sacrum embodiment;

FIG. 6 c shows an anatomical drawing of the needle inserted as shown inthe FIG. 6 b embodiment;

FIG. 6 d shows a patient having a guide wire inserted through theneedle;

FIG. 6 e shows an anatomical drawing of the guide wire inserted as shownin the FIG. 6 d embodiment;

FIG. 6 f shows a patient having a dilator placed over the guide wireembodiment;

FIG. 6 g shows an anatomical drawing of the dilator placed over theguide wire as shown in the FIG. 6 f embodiment;

FIG. 6 h shows a patient having the dilator inserted into the sacrumembodiment;

FIG. 6 i shows an anatomical drawing of the dilator inserted into thesacrum as shown in the FIG. 6 h embodiment;

FIG. 6 j shows preparation for inserting the stimulation lead into thedilator embodiment;

FIG. 6 k shows inserting the stimulation lead into the dilatorembodiment;

FIG. 6 l shows removal of the dilator embodiment;

FIG. 6 m shows creating an incision at the stimulation lead insertionsite embodiment;

FIG. 6 n shows marking the stimulation lead embodiment;

FIG. 6 o shows an anatomical cross-section drawing of marking thestimulation lead embodiment;

FIG. 6 p shows applying a lead anchor to the stimulation leadembodiment;

FIG. 6 q shows tunneling the stimulation lead embodiment;

FIG. 6 r shows fixation of the lead anchor to the lead body embodiment;

FIG. 6 s shows fixation of the lead anchor to fascia of the patientembodiment;

FIG. 7 a shows a flowchart of a fourth minimally invasive embodiment;

FIG. 7 b shows an anatomical cross-section of creating an incision andinserting the needle embodiment;

FIG. 7 c shows an anatomical cross-section of insertion of the guideembodiment;

FIG. 7 d shows an anatomical cross-section of the guide in place afterthe needle has been removed embodiment;

FIG. 7 e shows an anatomical cross-section of placement of thestimulation lead over the guide embodiment;

FIG. 7 f shows an anatomical cross-section of fixing the stimulationlead to a patient's fascia and removal of the guide embodiment;

FIG. 7 g shows an anatomical cross-section of closing the incision andtunneling the stimulation lead embodiment;

FIGS. 8 a-8 c shows a variation of the dilator of FIG. 3 e usable in anyof the procedures described herein comprising a dilator formed of theassembly of a dilator body and a dilator sheath;

FIG. 8 d shows a needle or foramen needle having a hub and depth marksalong the needle body;

FIG. 8 e shows a needle or foramen needle without a hub and with depthmarks along the needle body;

FIG. 8 f shows a guide wire having depth marks along its length;

FIG. 9 a shows a flowchart of a fifth minimally invasive methodembodiment employing the dilator of FIGS. 8 a-8 c along with the needleof FIGS. 3 a or 3 d;

FIG. 9 b shows inserting and guiding a needle, e.g., a foramen needle,comprising a hollow needle body and an obturator within the needle bodylumen to the sacral nerve site;

FIG. 9 c shows inserting and advancing a guide wire through the needlebody lumen after electrical testing and removal of the obturator fromthe needle body lumen;

FIG. 9 d shows advancing the dilator of FIG. 8 c over the guide wire tolocate the distal end of the guide wire at the sacral nerve and thenwithdrawing the guide wire from the dilator body lumen;

FIG. 9 e shows withdrawal of the dilator body from the dilator sheath;

FIG. 9 f shows advancing a neurostimulation lead through the dilatorsheath lumen to locate the distal neurostimulation electrodes into theforamen and into operative relation with the sacral nerve;

FIG. 9 g shows withdrawal of the dilator sheath over the stimulationlead body after electrical testing of the stimulation efficacy; and

FIG. 10 shows a flowchart of a sixth minimally invasive methodembodiment employing the dilator of FIGS. 8 a-8 c along with the needleof FIGS. 3 a or 3 d.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 c shows an environmental view of a sterile area in which theminimally invasive method for implanting a sacral stimulation lead canbe performed. The method can be performed in a wide variety of locations20 that have a sterile field and common medical instruments such as anoperating room, surgery center. The method and its many embodiments aretypically performed by a urologist 22, but can be performed by manyclinicians 22 trained in stimulation lead implantation. The patient 24is placed under local or general anesthesia. With local anesthesia, themethod can potentially be performed in a clinician's 22 office forgreater accessibility and reduced costs. A sacral stimulation lead canbe implanted for a variety a purposes such as to treat pelvic floordisorders. Pelvic floor disorders include urinary control disorders,fecal control disorders, sexual dysfunction, and pelvic pain.

FIG. 2 shows an embodiment of an implanted neurostimulator 26 tostimulate sacral nerves 27 located near the sacrum 28. The sacral nervesare assessable through an entry point 29 along an insertion path 33 intoa foramen 31 to reach a desired location 35. A neurostimulation systemcan include a stimulation lead 30, a lead anchor (FIG. 3 g), a leadextension 32, a trial stimulator (not shown), an implantableneurostimulator 26, a physician programmer (not shown), and a patientprogrammer (not shown). The stimulation lead 30 has electrical contacts34 positioned on the distal end to stimulate nerves and connectors (notshown) on the proximal end to connect to a lead extension or directly tothe trial neurostimulator or implantable neurostimulator 26. Thestimulation lead 30 can be a Medtronic Model 3886 quadrapolar leadwithout anchor having a diameter of approximately a 0.127 cm (0.050inch) and designed to accept a stylet through the center of thestimulation lead 30 to assist in insertion. The lead anchor (FIG. 3 f)fixes the stimulation lead 30 to prevent the stimulation lead 30 frommigrating away from the position selected by the implanting clinician22. The lead extension 32 connects between the stimulation lead 30 andthe trial stimulator or implantable stimulator 26. The trialneurostimulator tests the effectiveness of stimulation to treat thepatient's condition prior to implantation of an implantableneurostimulator 26.

The implantable neurostimulator 26 provides a programmable stimulationsignal that is delivered to a desired location or target to stimulateselected nerves. The implantable neurostimulator 26 is typicallyimplanted in a subcutaneous pocket around the upper buttocks sometimeafter the stimulation lead 30 has been implanted and its effectivenessverified. The physician programmer is used by the clinician 22 tocommunicate with the implantable neurostimulator 26 to program thestimulation signal produced by the implantable neurostimulator. Thepatient programmer allows the patient to communicate with theimplantable neurostimulator to control certain parameters of thestimulation signal typically selected by a clinician. With a pelvicfloor disorder, a patient can typically control stimulation signalparameters such as voltage amplitude. Neurostimulation systems with thecomponents discussed above are available from Medtronic, Inc. inMinneapolis, Minn.

FIGS. 3 a-3 g show some of the surgical instruments (not to scale)typically available to the implanting clinician to aid in implanting thestimulation lead 30, the instruments selected to form instrument kits ofthe present invention. Local anesthetic is delivered to the patienttypically with a syringe such as a Luer Slip Disposable 12 cc syringe(not shown). The needle 36 is selected based upon the needs of thepatient 24 typically ranging in size from an outer diameter of about 26gauge (0.46 mm) to about 12 gauge (2.80 mm) such as the 20 gauge (0.89mm), thin wall, foramen needle 38 Models 041828 and 041829 availablefrom Medtronic. The foramen needle 38 has a stylet 40, also known as anobturator, in the foramen needle 38 central opening and markings thatmeasure 1.0 cm increments and a wider mark at 5.0 cm to aid inpositioning needle depth. Additionally the foramen needle 38 tip andproximal portion adjacent to the hub are conductive, so a trialstimulator can be electrically connected to the hub. The trialstimulator stimulation signal will travel to the foramen needle 38 tipto evoke a response from the patient 24 to determine if the foramenneedle 38 is properly position and whether the patient 24 will likelybenefit from stimulation.

The dilators 42 can be metal or plastic dilators typically ranging insize from an outer diameter of about 5 French (0.33 mm) to about 14French (4.00 mm), such as an Angiocath® intravenous catheter placementunit available from Parke Davis & Company, selected based upon the sizeof stimulation lead 30 to be implanted. Multiple dilators 42 can be usedtypically in sequence from a smaller diameter to a larger diameter toachieve the desired dilation while controlling tissue trauma. The guidewire 44 is typically a thin biocompatible stainless steel wire with adiameter such as 0.076 cm (0.030 inch). Dilators 42 and guide wires 44are available in cardiac pacing lead introducer kits such as Medtronic'sModel 3208, Percutaneous Lead Introducer. The dilator 42 can be a metalor plastic dilator sized appropriately to pass the stimulation lead 30such as an 8 French (2.6 mm) sized dilator. The neurostimulation leadanchor 46 shown in FIG. 3 g over stimulation lead 30 is an implantablesurgical anchor configured to fix to the stimulation lead 30 such as asuture anchor or a twist-lock anchor available in the Medtronic Model3550-1 Boots and Anchors Accessory Kit or the silicone anchor includedin the Medtronic Model 3886 Lead Electrode Kit. Additionally to assistthe clinician 22 in guiding placement of the needle 36 and guide wire44, the clinician 22 may use a fluoroscope or x-ray machine.

First Minimally Invasive Method Embodiment

FIG. 4 shows a flowchart of a first embodiment of the minimally invasiveimplantation method employing a first instrument kit of the presentinvention. FIG. 2 shows an embodiment of an implanted neurostimulator 26to stimulate sacral nerves 27, and FIGS. 3 a-3 g show some surgicaltools that can be used to perform the minimally invasive method. Priorto beginning the first method for minimally invasive method embodiment48 for sacral electrical stimulation lead 30 implantation in a patient24, the following preparatory actions are typically taken. A localanesthetic is typically applied to anesthetize the area where thestimulation lead 30 will be implanted such as posterior to the sacrum28. Since embodiments of the method permit use of a local anesthetic,patients 24 can be treated on an outpatient basis to greatly reducescosts over inpatient care and reduce recovery time. This significantcost reduction also makes sacral stimulation lead 30 implantation andits many beneficial therapies available to more patients 24 becausehealthcare payers are more likely to cover procedure costs. Also byusing local anesthesia, the implanting clinician 22 can use thepatient's 24 conscious sensory response to stimuli such as trialstimulation to aid in placing the stimulation lead 30. By using thepatient's 24 conscious sensory response during stimulation lead 30placement, the stimulation lead 30 can be more accurately placedreducing the potential for an ineffective therapy and reducing thepotential for patient 24 injury caused by a misplaced lead 30. Otherforms of anesthesia can also be used such as general anesthesia. Oncethe patient 24 has been anesthetized, the first method embodiment 48 canbegin.

A needle 36 is inserted 50 posterior to the sacrum 28 through an entrypoint 29 typically created with the needle 36. The needle 36 can take avariety of forms such as a needle without a hub (cannula), a solid rodwith a sharp tip, a needle with a hub that can be removed for example bya cutting tool, or a foramen needle 38 modified to have an extendedlength and a hub that can be removed with a cutting tool. The entrypoint 29 is typically a percutaneous entry created when the needle 36 isinserted. The needle 36 is hand guided 52 into the foramen 31 along aninsertion path 33 to a desired location 35. The foramen's 31 approximatelocation can be found using anatomical landmarks, fluoroscopy, orx-rays. When guiding 52 the needle 36, the position of the needle 36 canbe sensed by a variety of means such as by applying an electrical signalto the needle 36 to evoke a patient 24 response such as a motor orsensory response. Once the needle 36 is in position, the needle 36 canremain in the position to serve as a guide for the dilator 42, or in thealternative a guide wire 44 can be inserted through the needle 36. Whenthe needle 36 is used as a guide for the dilator 42, the needle hub 45typically must be removed before the dilator 42 can be guided over theneedle 36. Alternatively, a guide wire 44 can be used as the guide forthe dilator 42. The guide wire 44 can be a flexible guide wire, a stiffguide wire, or a stylet. Once the guide wire 44 is in position, theneedle 36 can be removed, and the guide wire 44 can serve as a guide forthe dilator 42.

The insertion path 33 is dilated 54 with a dilator 42 to a diametersufficient for inserting a stimulation lead 30. The needle 36 is removed56 from the insertion path 33, or alternatively the guide wire 44 isremoved 56 from the insertion path 33. When removing 56 the needle 36from the insertion path 33, care should be taken to avoid displacing thedilator 42. The stimulation lead 30 is inserted 58 to the desiredlocation 35. Since the chronic stimulation lead 30 is being inserted 58directly without the requirement for a separate test stimulation lead(not shown), such as a Medtronic Test Simulation Lead Model 3057, thechronic stimulation lead 30 can be placed without positioningrepeatability variation. Also, there is a greater correlation betweenacute test stimulation and chronic therapy stimulation because the samelead 30 is performing both test stimulation and therapy stimulation. Thedesired location 35 can be any area of the sacrum 28 intended to achievea therapeutic effect such as into the foremen 31. One way to verify thestimulation lead's 30 position is to apply an electrical signal to thestimulation lead 30 to evoke a patient 24 motor or sensory response.Other ways to verify the stimulation lead's 30 position include imagingtechniques such as fluoroscopy and x-ray. When inserting 58 theimplantable stimulation lead 30, the lead 30 is advanced through thedilator 42 to the desired location 35 for stimulation. The dilator 42 isremoved 60 from the insertion path 33. When removing 60 the dilator 42from the insertion path 33, care should be taken to avoid displacing thestimulation lead 30. Additionally, stimulation lead 30 position shouldbe re-verified by one of the previously discussed techniques. Once thedilator 42 is removed, the clinician 22 may decide that the lead 30 doesnot need to be fixed because the patient's 24 physiology itselfadequately stabilizes the lead 30. When the stimulation lead 30 is notseparately fixed, patient 24 tissue disruption is minimized whichprovides for faster patient 24 recovery and potentially less stimulationlead 30 migration caused by disrupted tissue changes. If the clinician22 does not wish to separately fix the stimulation lead 30, the firstmethod embodiment 48 is completed. Optionally, the clinician 22 canseparately fix the stimulation lead 30 by creating an incision 62,anchoring the lead 64, and closing the incision 66.

FIG. 5 h shows an embodiment for separately fixing the stimulation lead.To separately fix the stimulation lead 30, an incision 68 through theentry point 29 is created from an epidermis 70 to a fascia layer 72 suchas the lumbosacral fascia layer. This incision 68 can also be created ata later point in the method embodiment 48 without adversely affectingthe method. The stimulation lead 30 is anchored 64 to the fascia layer72. When anchoring 64 the stimulation lead 64 care is again should betaken to avoid displacing the stimulation lead 30. Finally, the incision68 created for the anchor is closed 66. Since the first methodembodiment 48 disrupts less tissue than the prior art method, patient 24tissue disruption is minimized which provides for faster patientrecovery and potentially less stimulation lead 30 migration caused bydisrupted tissue changes.

A portion of the first minimally invasive method embodiment 48 can alsobe used simply for stimulation lead 30 placement for acute teststimulation rather than implantation. For stimulation lead 30 placement,typically the same procedure is used as for implantation throughremoving the dilator 60 from the insertion path 33. Once the dilator 42is removed, stimulation lead 30 placement is validated to ensure thestimulation lead 30 is in the desired location 35.

Second Minimally Invasive Method Embodiment

FIG. 5 a shows a flowchart of a second minimally invasive implantationmethod embodiment 74, and FIGS. 5 b-5 k show various implementationelement embodiments. The second minimally invasive method embodiment 74is similar to the first minimally invasive method embodiment 48 with theexception that in the second method embodiment 74 includes an incisionfor anchoring that is created 62 after the needle has been guided 52 toa desired location 35 that is optional in the first method embodiment48. By making the incision 62 earlier than optionally performed in thefirst minimally invasive method 48, the stimulation lead 30 can be moreeasily anchored 64 to a fascialu layer 72 such as the lumbosacral fascialayer closer to the stimulation lead 30 distal end.

A portion of the second minimally invasive method embodiment 74 can alsobe used simply for stimulation lead 30 placement for acute teststimulation rather than implantation. For stimulation lead 30 placement,typically the same procedure is used as for implantation throughremoving the dilator 60 from the insertion path 33. Once the dilator isremoved 60, stimulation lead 30 placement is validated to ensure thestimulation lead 30 is in the desired location 35.

Third Minimally Invasive Method Embodiment

FIG. 6 a shows a flowchart of a third minimally invasive implantationmethod embodiment 76, and FIGS. 6 b-6 o show various implementationelement embodiments. The third minimally invasive method embodiment 76is similar to the first minimally invasive method embodiment 48 with theexception that a guide wire 44, stylet, or long needle is inserted 78 toguide the dilator 42 and the guide wire 44 is removed 80 after dilationhas been completed. More specifically, after the needle 36 has beenguided 52 into the foramen along an insertion path 33 to a desiredlocation 35, a guide wire 44 is inserted into the needle 36 to thedesired location 35. Once the guide wire 44 is in place, the needle 36is removed 56 while retaining the guide wire 44 at the desired location35. The dilator 42 is placed over the guide wire 44 along the insertionpath 33 to dilate 54 the insertion path 33 to a diameter sufficient forinserting 58 a stimulation lead 30. Once the dilator 42 is in place, theguide wire 44 is removed 80 from the dilator 42. After the stimulationlead 30 is in the desired location 35, the dilator 42 is removed 60.With the third minimally invasive method 76, once the dilator 42 isremoved 60, the additional steps of creating an incision 62, anchoringthe lead 64, and closing the incision 66 are optional. Once the dilator42 is removed 60, the clinician 22 may decide that the stimulation lead30 does not need to be fixed because the patient's 24 physiology itselfadequately stabilizes the stimulation lead 30. If the clinician 22determines the patient 24 requires the stimulation lead 30 fixation,then the clinician 22 would perform the elements of creating an incision62, anchoring the lead 64, and closing the incision 66 as discussedpreviously.

A portion of the third minimally invasive method embodiment 76 can alsobe used simply for stimulation lead 30 placement for acute teststimulation rather than implantation. For stimulation lead 30 placement,typically the same procedure is used as for implantation throughremoving 60 the dilator 42 from the insertion path. Once the dilator 42is removed 60, stimulation lead 30 placement is validated to ensure thestimulation lead 30 is in the desired location 35.

Fourth Minimally Invasive Method Embodiment

FIG. 7 a shows a flowchart of a fourth minimally invasive implantationmethod embodiment 82, and FIGS. 7 b-7 g show various implementationelement embodiments. The fourth minimally invasive method embodiment 82is similar to the second minimally invasive method embodiment 74 withthe exception that a guide wire 44 or stylet is inserted 78 to guide thestimulation lead 30 and the stimulation lead 30 functions as the dilator42, so a separate dilator 42 is not used. More specifically, after theincision 68 is created 62, a guide wire 44 is inserted 78 into theneedle. Once the guide wire 44 is in the desired location 35, the needle36 is removed 56 from the insertion path 33. In one embodiment, thestimulation lead 30 is configured with a centrally located stylet lumenand a pointed tip, so the stimulation lead 30 can serve as the dilator42. The stimulation lead 30 stylet lumen is inserted 58 over the guidewire 44 and the stimulation lead 30 is advanced to the desired location35. After the stimulation lead 30 is in the desired location 35, theguide wire 44 is removed 80 from the stimulation lead 30. Then thestimulation lead 30 is anchored 64 and the incision 68 is closed 66similar to the second minimally invasive method embodiment 74.

A portion of the fourth minimally invasive method embodiment 82 can alsobe used simply for stimulation lead 30 placement for acute teststimulation rather than implantation. For stimulation lead 30 placement,typically the same procedure is used as for implantation throughremoving 80 the guide wire 44 from the stimulation lead 30. Once theguide wire 44 is removed, stimulation lead 30 placement is validated toensure the stimulation lead 30 is in the desired location 35.

Fifth and Sixth Minimally Invasive Method Embodiments

The above described instrument kits used in the first through fourthembodiments are modified by substitution of a dilator 42′ formed of theassembly of a dilator body 47 and a dilator sheath 49 as shown in FIGS.8 a-8 c. The dilator body 47 is preferably conductive, and the dilatorsheath 49 is preferably non-conductive but may bear radiopaque andvisually observable depth marks 51 along its length to facilitateradiographic imaging when it is extended into the patient's body. Thedepth markings or marks 51 can be one centimeter or one-half centimeterbands or numerals or other indicia that indicate the depth of insertionto clinician from the exposed marking. The most distal mark is spacedfrom the distal tip of dilator sheath 49 to indicate a predetermineddepth of the distal tip of the dilator body 47 protruding distallyduring insertion as shown in FIG. 8 c.

Thus, when assembled as shown in FIG. 8 c, the dilator body distal endextends out of the dilator sheath distal end and is electricallyexposed. Electrical stimulation of the sacral nerve to test placementcan take place through the dilator body 47 while the dilator sheath 49is in place

The dilator body 47 has a dilator body diameter, a dilator body lengthextending between a dilator proximal end and a dilator distal end, and adilator body lumen extending from the dilator proximal end to thedilator distal end. The dilator sheath has a dilator sheath diameter, adilator sheath length extending between a dilator sheath proximal endand a dilator sheath distal end. A dilator sheath lumen extends from thedilator sheath proximal end to the dilator sheath distal end, thedilator sheath lumen having a dilator sheath lumen diameter sized inoperative relation to the dilator body diameter to selectively receivethe dilator body therein to assemble the dilator body and dilator sheathas the dilator as shown in FIG. 8 c. The dilator sheath lumen is alsosized in operative relation to the diameter of the neurostimulation leadbody so that the neurostimulation lead can be advanced through thedilator sheath.

The needle 36 or foramen needle 38 is also shown in FIG. 8 d with a hub45 and with depth marks 53 in FIG. 8 e and without a hub and with depthmarks 55. The guide wire 44 is also shown in FIG. 8 f. marked withfurther depth marks 57. In addition, the body of the neurostimulationlead 30 is marked with depth marks. The depth mark 53′ is widened orotherwise made distinguishable to indicat a particular depth, e.g., 5cm, to assist the clinician in keeping track of the marks 53.

These depth marks 53, 55, 57 are correlated to one another and to thedepth marks 51 so that the depth of insertion from the skin of eachinstrument is ascertainable from the proximal exposed marks. These marks53, 55, 57 can be observed to maintain the depth while manipulating theinstruments to assure that the clinician extends each instrument to thesame depth. Similarly, the depth marks on the neurostimulation lead 30are correlated to the length of the dilator 42 or the dilator sheath 49to properly locate a neurostimulation lead electrode in operativerelation to the sacral nerve. and lead electrode(s)

For example, one of the depth marks of each set can be widened orotherwise made distinguishable from the others so that the clinician cantell when the distal end or distal electrode(s) of the instrument orlead introduced through the lumen or over an instrument already placedto the site is properly positioned at the site. In FIG. 8 f, a mark 57′is placed along the guide wire body at a distance from the distal endthat, when exposed from the needle hub 45 or a dilator hub indicatesthat the distal end of the guide wire 44 is positioned at the distal endof the needle 36, 38 or dilator 42′. Conversely, a dilator 42, 42′ orlead 30 is inserted over the guide wire 44 until the mark 57′ is exposedshowing that the distal end of the dilator 42, 42′ or lead 30 isproperly advanced over the guide wire 44 to the desired site. Similarly,in a variation where a dilator 42 or 42′ is inserted over the needle 36,38 depicted in FIG. 8 e, a mark 55′ placed along the needle body at adistance from the distal end is exposed from the dilator hub thatsignifies that the dilator distal tip is at the desired site.

The needle 36, 38, dilator 42′ and guide wire 44 are all preferablyformed of a conductive material insulated along the exposed lengthsthereof but exposed at or along the proximal and distal ends thereof soas to be capable of being used to conduct test stimulation to the sacralnerve to assess the efficacy of stimulation prior to implantation of theneurostimulation lead and to establish the depth of positioning of theneurostimulation lead electrode. For example, an exposed distalelectrode 59 and an exposed proximal connector element 63 is depicted onneedle 36, 38 in FIG. 8 e, and an exposed distal electrode 61 and anexposed proximal connector element 65 is depicted on guide wire 44 inFIG. 8 f. The dilator body lumen has a dilator body lumen diameter sizedin operative relation to the diameter of guide wire 44 or needle 36 or38 so that the assembled dilator can be advanced over the guide wire 44in accordance with the method depicted in FIG. 9 a or over the needle 36or 38 in accordance with the method depicted in FIG. 10.

FIG. 9 a shows a flowchart of a fifth minimally invasive methodembodiment employing the dilator 42′ of FIGS. 8 a-8 c along with theneedle 36 of FIGS. 3 a and 8 or foramen needle 38 of FIG. 3 d and aguide wire 44. Many of the steps of FIG. 9 a are common to the steps ofFIGS. 4, 5 a, 6 a, and 7 a, and commonly enumerated. FIG. 9 b showsinserting and guiding a needle 36, e.g., a foramen needle 36, comprisinga hollow needle body and a stylet or obdurator 40 within the needle bodylumen, to the sacral nerve site in accordance with steps 50 and 52. Theneedle 36, 38 is electrically insulated along its length except alongthe distal tip and preferably has depth marks spaced along the needleshaft or body as described above that the clinician observes whileadvancing the needle distal tip to the desired location 35 within orthrough the foramen and adjoining the sacral nerve. The proximal end ofthe obdurator 40 can be coupled to a neurostimulator to deliverneurostimulation to test the stimulation efficacy at the location 35.

FIG. 9 c shows inserting and advancing a guide wire 44 through theneedle body lumen after electrical testing and removal of the obdurator40 from the needle body lumen in accordance with step 78. The guide wire44 is advanced until the guide wire marking 57′ abuts the needle hub 45or needle proximal end if a needle 36, 38 of the type depicted in FIG. 8e is employed. FIG. 9 c also shows withdrawal of the needle 36, 38 overthe guide wire 44 in accordance with step 56, leaving the guide wire 44in place extending from its distal end at the desired location 35 andits proximal end projecting from the patient's skin.

Preferably, the guide wire 44 is stiff and straight and is long enoughso that the dilator 42′ can be inserted over the guide wire 44 outsideof the patient's skin. The proximal end of the guide wire 44 can then begrasped as the dilator 42′ is advanced over and past it. FIG. 9 d showsadvancing the dilator 42′ of FIG. 8 c over the guide wire 44 to locatethe distal end of the guide wire 44 at the desired location 35 adjoiningthe sacral nerve in accordance with step 90 and then withdrawing theguide wire 44 from the dilator body lumen in accordance with step 80.Again, the dilator 42′ is advanced distally over the guide wire 44 untilthe mark 57′ is exposed, which indicates that the dilator body distalend is at the desired location 35.

FIG. 9 e shows withdrawal of the dilator body 47 from the dilator sheath49 in accordance with step 92. The depth marking on the dilator sheathsurface exposed at the skin incision is observed to ensure that thedilator sheath 49 is not inadvertently advanced or withdrawn as thedilator body is withdrawn.

FIG. 9 f shows advancing a neurostimulation lead 30 through the dilatorsheath lumen to locate the distal neurostimulation electrode(s) into theforamen and into operative relation with the sacral nerve at the desiredsite 35 in accordance with step 58. The depth marking on the lead bodyexposed at the proximal dilator sheath hub can be employed to ensurethat the lead electrode(s) has exited the dilator sheath distal end butis not advanced too far.

FIG. 9 g shows withdrawal of the dilator sheath 49 over the stimulationlead body after electrical testing of the stimulation efficacy throughthe lead 30 in accordance with step 94. Then, steps 62, 64 and 66 can befollowed as described above to complete the implantation of theneurostimulation lead and implantable neurostimulator. As noted above,step 62 of forming the incision can optionally be performed betweensteps 52 and 78. Or, step 62 can be performed while the dilator sheath49 is in place after step 92 or step 58 or FIG. 9 a.

FIG. 10 shows a flowchart of a sixth minimally invasive methodembodiment employing the dilator 42′ of FIGS. 8 a-8 c along with theneedle 36 of FIG. 3 a or the foramen needle 38 of FIG. 3 d. In thisvariation, the guide wire 44 is not employed, and needle 36, 38 iseither not provided with a hub 45 or the hub 45 is cut off after step52. The assembled dilator 42′ is inserted over the needle 36, 38, instep 90′, and the needle is withdrawn in step 56. The remaining steps ofFIG. 10 are common with those of FIG. 9 a using the instruments as shownin the related illustrations of FIGS. 9 b-9 g as described above.

Thus, embodiments of a minimally invasive sacral lead implantationinstrumentation kits are disclosed with many benefits. Embodiments ofthe instrumentation kits can reduce patient surgical complications,reduce patient recovery time, and reduce healthcare costs. One skilledin the art will appreciate that the present invention can be practicedwith embodiments other than those disclosed. The disclosed embodimentsare presented for purposes of illustration and not limitation, and thepresent invention is limited only by the claims that follow.

1. A surgical instrumentation kit for minimally invasive implantation ofa sacral stimulation lead through a foramen of the sacrum in a patientto electrically stimulate a sacral nerve, the sacral stimulation lead ofthe type having a lead body extending between a lead body proximal endand a lead body distal end, the lead body having a lead body diameterextending from the lead body proximal end and lead body distal end, thelead body further enclosing at least one electrical conductor extendingbetween at least one proximally located electrical connector adapted tobe coupled to an electrical stimulation pulse generator and at least onedistally located stimulation electrode adapted to apply electricalstimulation to a sacral nerve, the kit comprising: a sacral stimulationlead; and a needle having a needle diameter and needle length extendingfrom a needle distal end capable of penetrating body tissue and a needleproximal end, the needle adapted to be grasped by a medical clinicianwith the needle distal end directed toward and inserted through an entrypoint of the skin or a skin incision posterior to the sacrum and guidedalong an insertion path into a foramen to locate at least a distalportion of the needle extending alongside a sacral nerve and a proximalportion of the needle extending from the entry point away from thepatient's skin; and a dilator having a dilator body diameter, a dilatorbody length extending between a dilator proximal end and a dilatordistal end, and a dilator body lumen extending from the dilator proximalend to the dilator distal end and having a dilator body lumen diametersized in operative relation to the lead body diameter and the needlediameter to selectively receive the needle and the lead body therein,wherein the dilator is adapted to be inserted over the needle proximalend to locate the needle within the dilator body lumen and to beadvanced distally over the needle through the insertion path to dilatethe insertion path to the dilator diameter, the needle is adapted to bewithdrawn through the dilator body lumen, the stimulation lead isadapted to be advanced through the dilator body lumen to locate thestimulation lead electrode into operative relation to the sacral nerve,and the dilator is adapted to be withdrawn over the stimulation leadbody, wherein if the needle proximal end comprises a hub, the hub is cutoff prior to inserting the dilator over the needle proximal end, whereinthe needle body comprises depth marks enabling visualization of thedepth of insertion of the needle through the insertion path, wherein thedilator body comprises depth marks, and wherein the needle body depthmarks correlate to the dilator body depth marks so that the depth ofinsertion from the skin of both the needle body and the dilator isascertainable from an exposed needle body depth mark and an exposeddilator body depth mark.
 2. The kit as in claim 1, wherein the needlefurther comprises an electrically conductive needle body providing adistal electrical stimulation electrode end and a proximal electricalconnector, the needle body electrically insulated in a region grasped bythe medical clinician between the electrical stimulation electrode andelectrical connector, whereby the distal needle body location inrelation to a sacral nerve can be assessed by delivering electricalstimulation through the needle to evoke a patient response signifyingthe distal needle body location.
 3. The kit as in claim 1, wherein theneedle diameter is in the range from about 0.46 mm to about 2.80 mm. 4.The kit as in claim 1, wherein the dilator diameter is in the range fromabout 0.33 mm to about 4.00 mm.
 5. The kit as in claim 1, wherein theneedle is selected from the group consisting of a needle without a hub,a needle with a removable hub, a solid rod with a sharp tip, and aforamen needle.
 6. The kit as in claim 1, further comprising an anchorselected from the group consisting of a suture anchor and a twist-locksuture anchor for anchoring the stimulation lead to the fascia layerupon withdrawal of the dilator over the stimulation lead body.
 7. Asurgical instrumentation kit for minimally invasive implantation of asacral stimulation lead through a foramen of the sacrum in a patient toelectrically stimulate a sacral nerve, the sacral stimulation lead ofthe type having a lead body extending between a lead body proximal endand a lead body distal end, the lead body having a lead body diameterextending from the lead body proximal end and lead body distal end, thelead body further enclosing at least one electrical conductor extendingbetween at least one proximally located electrical connector adapted tobe coupled to an electrical stimulation pulse generator and at least onedistally located stimulation electrode adapted to apply electricalstimulation to a sacral nerve, the kit comprising: a sacral stimulationlead; and a needle having a needle diameter and needle length extendingfrom a needle distal end capable of penetrating body tissue and a needleproximal end, the needle adapted to be grasped by a medical clinicianwith the needle distal end directed toward and inserted through an entrypoint of the skin or a skin incision posterior to the sacrum and guidedalong an insertion path into a foramen to locate at least a distalportion of the needle extending alongside a sacral nerve and a proximalportion of the needle extending from the entry point away from thepatient's skin; and a dilator having a dilator body diameter, a dilatorbody length extending between a dilator proximal end and a dilatordistal end, and a dilator body lumen extending from the dilator proximalend to the dilator distal end and having a dilator body lumen diametersized in operative relation to the lead body diameter and the needlediameter to selectively receive the needle and the lead body therein sothat the dilator is insertable over the needle proximal end to locatethe needle within the dilator body lumen to be capable of being advanceddistally over the needle through the insertion path to dilate theinsertion path to the dilator diameter and to allow the needle to bewithdrawn through the dilator body lumen and to allow the stimulationlead to be advanced through the dilator body lumen to locate thestimulation lead electrode in operative relation to the sacral nerve andto allow the dilator to be withdrawn over the stimulation lead body,wherein if the needle proximal end comprises a hub, the hub is cut offprior to inserting the dilator over the needle proximal end, wherein theneedle body comprises depth marks enabling visualization of the depth ofinsertion of the needle through the insertion path, wherein the dilatorbody comprises depth marks, and wherein the needle body depth markscorrelate to the dilator body depth marks so that the depth of insertionfrom the skin of both the needle body and the dilator is ascertainablefrom an exposed needle body depth mark and an exposed dilator body depthmark.
 8. The kit as in claim 7, further comprising: means for creatingan incision through the entry point of the epidermis to a fascia layer;means for anchoring the stimulation lead to the fascia layer uponwithdrawal of the dilator over the stimulation lead electrode; and meansfor closing the incision.
 9. The kit as in claim 7, wherein the needlefurther comprises an electrically conductive needle body providing adistal electrical stimulation electrode and a proximal electricalconnector, the needle body electrically insulated in a region grasped bythe medical clinician between the electrical stimulation electrode andelectrical connector, whereby the distal needle body location inrelation to a sacral nerve can be assessed by delivering electricalstimulation through the needle to evoke a patient response signifyingthe distal needle body location.
 10. The kit as in claim 7, wherein theneedle diameter is in the range from about 0.46 mm to about 2.80 mm. 11.The kit as in claim 7, wherein the dilator diameter is in the range fromabout 0.33 mm to about 4.00 mm.
 12. The kit as in claim 7, wherein theneedle is selected from the group consisting of a needle without a hub,a needle with a removable hub, a solid rod with a sharp tip, and aforamen needle.
 13. The kit as in claim 7, further comprising an anchorselected from the group consisting of a suture anchor and a twist-locksuture anchor for anchoring the stimulation lead to the fascia layerupon withdrawal of the dilator over the stimulation lead body.